Low vitamin D is common in Australia, even in a sunny country, and it can be part of why you feel flat. Here's who's at risk, what the signs are and how it's checked.
Low vitamin D can be part of why you feel tired, flat or achy, and it's surprisingly common in Australia despite all the sunshine. It doesn't usually cause tiredness on its own, but it often sits alongside other things such as poor sleep, low iron or a busy indoor lifestyle. The only way to know your level is a simple blood test, and a doctor can help you work out whether it's part of your picture.
What vitamin D actually does
Vitamin D is best known for helping your body absorb calcium and keep bones strong. It also plays a role in how muscles work and in the immune system. Your body makes most of its vitamin D when sunlight hits your skin, and only a small amount comes from food such as oily fish, eggs and fortified products.
That's why your level tends to follow your lifestyle and the season. It drops through winter, especially in places like Melbourne, Hobart and Adelaide, and in anyone who spends most of their day inside.
Signs that can point to low vitamin D
Mildly low vitamin D often causes no obvious symptoms at all. When levels are lower, people sometimes notice the following.
- Tiredness or a general sense of feeling flat
- Muscle weakness or aches
- Bone or joint discomfort
- Picking up colds and bugs more often
- Low mood, particularly through winter
None of these are specific to vitamin D. They overlap with many other common causes of tiredness, which is why guessing rarely helps. Low iron, thyroid changes, blood sugar problems and poor sleep can all look very similar. Our article on iron and tiredness explains one of the most common of these.
Who is more likely to be low
Some people are more likely to run low.
- People who work indoors or do shift work and rarely get daylight
- People with darker skin, which needs more sun to make the same amount of vitamin D
- People who cover most of their skin when outdoors
- Older adults, as skin makes vitamin D less efficiently with age
- People carrying extra weight, as vitamin D is stored in body fat
- People with conditions that affect absorption, such as coeliac disease
- Anyone in the southern half of Australia, especially in winter
How it's checked
A blood test measures your vitamin D level directly. It's often done alongside other tests when someone is tired, such as a full blood count, iron studies, thyroid function and blood sugar markers. Looking at these together gives a far clearer picture than any single result. Our guide to blood tests for fatigue explains what's commonly checked and why.
If your level comes back low, a doctor can talk you through sensible next steps and when it's worth rechecking. They'll also consider why it's low, because that often points to other things worth looking at.
Sun, food and everyday habits
Safe sun exposure is the main natural source of vitamin D, but Australia also has some of the highest skin cancer rates in the world, so balance matters. Cancer Council Australia's general guidance is that when the UV index is 3 or above, which is most of the year in much of the country, sun protection is recommended and most people get enough vitamin D from everyday incidental exposure. In the southern states during winter, when UV is lower, a little midday sun on the arms and face on most days can help.
Food helps a little too. Oily fish such as salmon and sardines, eggs and some fortified foods contain vitamin D, although it's hard to get enough from diet alone.
Daylight has other benefits for energy as well. Morning light helps set your body clock, which can make sleep and afternoon energy steadier. If you're often flat by mid afternoon, our article on the afternoon slump covers why that happens.
When to talk to a doctor
It's worth seeing a doctor if you've felt tired for more than a few weeks, especially if you also have muscle weakness, bone pain, frequent infections or low mood. Mention if you rarely get outdoors, have darker skin, have a condition that affects absorption or take medicines that might affect vitamin D. Please don't take high doses of supplements without advice, as too much vitamin D can cause its own problems.
If you have chest pain, trouble breathing or feel faint, call 000.
How UHD BioHealth can help
UHD BioHealth is a doctor-led telehealth service available across Australia. You start with a detailed online questionnaire about your energy, sleep and lifestyle, and an AHPRA-registered doctor reviews it within 24 hours. Where it's useful, your doctor will recommend bloodwork you can do locally, then you receive a written personalised plan with every cost listed before you pay anything, checked by a second, independent doctor. The questionnaire and doctor review are free, and you can start here.
Common questions
How common is low vitamin D in Australia?
More common than most people expect. National health surveys have found that around one in four Australian adults has low vitamin D, and it's more common in winter, in the southern states and in people who spend most of the day indoors.
Should I just start taking a vitamin D supplement?
It's worth talking to a doctor first. Tiredness has many possible causes, and a blood test can show whether vitamin D is actually low. If it is, your doctor can suggest how much to take and when to recheck, because more is not always better.
Is a vitamin D blood test covered by Medicare?
Medicare covers vitamin D testing for people with certain risk factors, such as very limited sun exposure, darker skin, some medical conditions or medicines that affect vitamin D. Otherwise there may be a cost. Your doctor can tell you which applies to you.
Running on empty by 3pm
An in-depth health questionnaire covering your history, symptoms, medications and lifestyle, read by an AHPRA-registered doctor within 24 hours. Bloodwork where it's needed, and a written plan before you pay anything.
Not ready for that yet? Get our free guide, What a doctor checks when you're always tired.
General health information only, not medical advice. Complete our questionnaire and a doctor will assess whether a consult is right for you. Individual needs and outcomes vary. In an emergency, call 000.
Why am I always tired?
Constant tiredness usually has more than one cause, from sleep and stress to iron, thyroid and blood sugar. Here's what's worth looking at.
Could your thyroid be making you tired?
An underactive or overactive thyroid can both cause tiredness. Here's what the thyroid does, the signs to notice, and how it's checked.
Mitochondrial health, explained
Mitochondria turn food and oxygen into the energy your cells run on. Here's what they do, why they change with age, and what supports them.